XTR gear cables

I have an XTR gear cable set fitted to my bike and the shifting has always been great (although it may be a bikecebo effect where I simply convince myself that they're better than everything else because they're XTR).

I'm getting some new shifters and will need to change the cables but can't seem to find any XTR innera available on their own (just full sets with outers). I'm sure that you used to be able to buy XRT (and XT) inners separately; does anyone know where? If they're no longer available is there anything else that stands out, or are gear cable all much of a muchness?

Goodridge PTFE coated stainless cables are about £6 per pair, rather than £12 each like the Shimano ones.

In use, they work just the same... That is to say noticably better than cheapo cables. Pre lubed outers make a bit of a difference too IMO.

For the doubters out there, running good gear cables makes MUCH more of a difference to the shifting performance of the bike than the quality of the rear mech does. When you work in a shop, and fondle expensive customers bikes with cheap nasty gear cables that they bring in for a service, and wonder why their gears feel horrible, you learn the difference between cheap cables and decent ones pretty quickly!